The present invention relates in general to a method and device for clock calibration, and more particularly, to a method and device utilizing the inputted external clock signal to calibrate the internal generated clock signals.
Nowadays a computer becomes a daily use in almost every house. The computer can help people to do a lot of things and is playing an important role in the modern life. Some people usually work outside, a laptop computer is more convenient. The laptop computer can utilize an adapter connected to a plug for receiving power. When users take the laptop computer outside, the laptop computer can use a rechargeable battery to provide power.
With reference to FIG. 1, conventional rechargeable battery with a plurality of cells connected in series contains a rechargeable circuit and a protecting and detecting circuit. The protecting and detecting circuit includes a protecting unit and a power monitoring unit. The power monitoring unit communicates with the laptop computer to measure voltage, current and temperature of the battery, and determines the residual electricity of the battery to let users know when the battery needed to be recharged.
The protecting unit timely detects the voltage and current of the battery. If only one cell with lower voltage is detected, the protecting unit will stop all cells supplying power. Then, all cells are charged until the cell with higher voltage finishes charging; however, it may happen that the cell with lower voltage is still not charged enough. In other words, it is possible that not all the cells are charged to have a predetermined amount of electrical energy.
The power monitoring unit measures the quantity of electricity by multiplying the current running for a specified time detected by the clock signal. Conventional method utilizes an interior clock generator installed in the power monitoring unit to generate the clock signal. However, this kind of clock generator can not provide precise clock signal so that the measured quantity of electricity may not be accurate. Another method utilizes an exterior clock generator to input more precise clock signal; however, the cost is higher.